﻿/*!
 * jQuery hashchange event - v1.3 - 7/21/2010
 * http://benalman.com/projects/jquery-hashchange-plugin/
 * 
 * Copyright (c) 2010 "Cowboy" Ben Alman
 * Dual licensed under the MIT and GPL licenses.
 * http://benalman.com/about/license/
 */

// Script: jQuery hashchange event
//
// *Version: 1.3, Last updated: 7/21/2010*
// 
// Project Home - http://benalman.com/projects/jquery-hashchange-plugin/
// GitHub       - http://github.com/cowboy/jquery-hashchange/
// Source       - http://github.com/cowboy/jquery-hashchange/raw/master/jquery.ba-hashchange.js
// (Minified)   - http://github.com/cowboy/jquery-hashchange/raw/master/jquery.ba-hashchange.min.js (0.8kb gzipped)
// 
// About: License
// 
// Copyright (c) 2010 "Cowboy" Ben Alman,
// Dual licensed under the MIT and GPL licenses.
// http://benalman.com/about/license/
// 
// About: Examples
// 
// These working examples, complete with fully commented code, illustrate a few
// ways in which this plugin can be used.
// 
// hashchange event - http://benalman.com/code/projects/jquery-hashchange/examples/hashchange/
// document.domain - http://benalman.com/code/projects/jquery-hashchange/examples/document_domain/
// 
// About: Support and Testing
// 
// Information about what version or versions of jQuery this plugin has been
// tested with, what browsers it has been tested in, and where the unit tests
// reside (so you can test it yourself).
// 
// jQuery Versions - 1.2.6, 1.3.2, 1.4.1, 1.4.2
// Browsers Tested - Internet Explorer 6-8, Firefox 2-4, Chrome 5-6, Safari 3.2-5,
//                   Opera 9.6-10.60, iPhone 3.1, Android 1.6-2.2, BlackBerry 4.6-5.
// Unit Tests      - http://benalman.com/code/projects/jquery-hashchange/unit/
// 
// About: Known issues
// 
// While this jQuery hashchange event implementation is quite stable and
// robust, there are a few unfortunate browser bugs surrounding expected
// hashchange event-based behaviors, independent of any JavaScript
// window.onhashchange abstraction. See the following examples for more
// information:
// 
// Chrome: Back Button - http://benalman.com/code/projects/jquery-hashchange/examples/bug-chrome-back-button/
// Firefox: Remote XMLHttpRequest - http://benalman.com/code/projects/jquery-hashchange/examples/bug-firefox-remote-xhr/
// WebKit: Back Button in an Iframe - http://benalman.com/code/projects/jquery-hashchange/examples/bug-webkit-hash-iframe/
// Safari: Back Button from a different domain - http://benalman.com/code/projects/jquery-hashchange/examples/bug-safari-back-from-diff-domain/
// 
// Also note that should a browser natively support the window.onhashchange 
// event, but not report that it does, the fallback polling loop will be used.
// 
// About: Release History
// 
// 1.3   - (7/21/2010) Reorganized IE6/7 Iframe code to make it more
//         "removable" for mobile-only development. Added IE6/7 document.title
//         support. Attempted to make Iframe as hidden as possible by using
//         techniques from http://www.paciellogroup.com/blog/?p=604. Added 
//         support for the "shortcut" format $(window).hashchange( fn ) and
//         $(window).hashchange() like jQuery provides for built-in events.
//         Renamed jQuery.hashchangeDelay to <jQuery.fn.hashchange.delay> and
//         lowered its default value to 50. Added <jQuery.fn.hashchange.domain>
//         and <jQuery.fn.hashchange.src> properties plus document-domain.html
//         file to address access denied issues when setting document.domain in
//         IE6/7.
// 1.2   - (2/11/2010) Fixed a bug where coming back to a page using this plugin
//         from a page on another domain would cause an error in Safari 4. Also,
//         IE6/7 Iframe is now inserted after the body (this actually works),
//         which prevents the page from scrolling when the event is first bound.
//         Event can also now be bound before DOM ready, but it won't be usable
//         before then in IE6/7.
// 1.1   - (1/21/2010) Incorporated document.documentMode test to fix IE8 bug
//         where browser version is incorrectly reported as 8.0, despite
//         inclusion of the X-UA-Compatible IE=EmulateIE7 meta tag.
// 1.0   - (1/9/2010) Initial Release. Broke out the jQuery BBQ event.special
//         window.onhashchange functionality into a separate plugin for users
//         who want just the basic event & back button support, without all the
//         extra awesomeness that BBQ provides. This plugin will be included as
//         part of jQuery BBQ, but also be available separately.

(function ($, window, undefined) {
    '$:nomunge'; // Used by YUI compressor.

    // Reused string.
    var str_hashchange = 'hashchange',

      // Method / object references.
      doc = document,
      fake_onhashchange,
      special = $.event.special,

      // Does the browser support window.onhashchange? Note that IE8 running in
      // IE7 compatibility mode reports true for 'onhashchange' in window, even
      // though the event isn't supported, so also test document.documentMode.
      doc_mode = doc.documentMode,
      supports_onhashchange = 'on' + str_hashchange in window && (doc_mode === undefined || doc_mode > 7);

    // Get location.hash (or what you'd expect location.hash to be) sans any
    // leading #. Thanks for making this necessary, Firefox!
    function get_fragment(url) {
        url = url || location.href;
        return '#' + url.replace(/^[^#]*#?(.*)$/, '$1');
    };

    // Method: jQuery.fn.hashchange
    // 
    // Bind a handler to the window.onhashchange event or trigger all bound
    // window.onhashchange event handlers. This behavior is consistent with
    // jQuery's built-in event handlers.
    // 
    // Usage:
    // 
    // > jQuery(window).hashchange( [ handler ] );
    // 
    // Arguments:
    // 
    //  handler - (Function) Optional handler to be bound to the hashchange
    //    event. This is a "shortcut" for the more verbose form:
    //    jQuery(window).bind( 'hashchange', handler ). If handler is omitted,
    //    all bound window.onhashchange event handlers will be triggered. This
    //    is a shortcut for the more verbose
    //    jQuery(window).trigger( 'hashchange' ). These forms are described in
    //    the <hashchange event> section.
    // 
    // Returns:
    // 
    //  (jQuery) The initial jQuery collection of elements.

    // Allow the "shortcut" format $(elem).hashchange( fn ) for binding and
    // $(elem).hashchange() for triggering, like jQuery does for built-in events.
    $.fn[str_hashchange] = function (fn) {
        return fn ? this.bind(str_hashchange, fn) : this.trigger(str_hashchange);
    };

    // Property: jQuery.fn.hashchange.delay
    // 
    // The numeric interval (in milliseconds) at which the <hashchange event>
    // polling loop executes. Defaults to 50.

    // Property: jQuery.fn.hashchange.domain
    // 
    // If you're setting document.domain in your JavaScript, and you want hash
    // history to work in IE6/7, not only must this property be set, but you must
    // also set document.domain BEFORE jQuery is loaded into the page. This
    // property is only applicable if you are supporting IE6/7 (or IE8 operating
    // in "IE7 compatibility" mode).
    // 
    // In addition, the <jQuery.fn.hashchange.src> property must be set to the
    // path of the included "document-domain.html" file, which can be renamed or
    // modified if necessary (note that the document.domain specified must be the
    // same in both your main JavaScript as well as in this file).
    // 
    // Usage:
    // 
    // jQuery.fn.hashchange.domain = document.domain;

    // Property: jQuery.fn.hashchange.src
    // 
    // If, for some reason, you need to specify an Iframe src file (for example,
    // when setting document.domain as in <jQuery.fn.hashchange.domain>), you can
    // do so using this property. Note that when using this property, history
    // won't be recorded in IE6/7 until the Iframe src file loads. This property
    // is only applicable if you are supporting IE6/7 (or IE8 operating in "IE7
    // compatibility" mode).
    // 
    // Usage:
    // 
    // jQuery.fn.hashchange.src = 'path/to/file.html';

    $.fn[str_hashchange].delay = 50;
    /*
    $.fn[ str_hashchange ].domain = null;
    $.fn[ str_hashchange ].src = null;
    */

    // Event: hashchange event
    // 
    // Fired when location.hash changes. In browsers that support it, the native
    // HTML5 window.onhashchange event is used, otherwise a polling loop is
    // initialized, running every <jQuery.fn.hashchange.delay> milliseconds to
    // see if the hash has changed. In IE6/7 (and IE8 operating in "IE7
    // compatibility" mode), a hidden Iframe is created to allow the back button
    // and hash-based history to work.
    // 
    // Usage as described in <jQuery.fn.hashchange>:
    // 
    // > // Bind an event handler.
    // > jQuery(window).hashchange( function(e) {
    // >   var hash = location.hash;
    // >   ...
    // > });
    // > 
    // > // Manually trigger the event handler.
    // > jQuery(window).hashchange();
    // 
    // A more verbose usage that allows for event namespacing:
    // 
    // > // Bind an event handler.
    // > jQuery(window).bind( 'hashchange', function(e) {
    // >   var hash = location.hash;
    // >   ...
    // > });
    // > 
    // > // Manually trigger the event handler.
    // > jQuery(window).trigger( 'hashchange' );
    // 
    // Additional Notes:
    // 
    // * The polling loop and Iframe are not created until at least one handler
    //   is actually bound to the 'hashchange' event.
    // * If you need the bound handler(s) to execute immediately, in cases where
    //   a location.hash exists on page load, via bookmark or page refresh for
    //   example, use jQuery(window).hashchange() or the more verbose 
    //   jQuery(window).trigger( 'hashchange' ).
    // * The event can be bound before DOM ready, but since it won't be usable
    //   before then in IE6/7 (due to the necessary Iframe), recommended usage is
    //   to bind it inside a DOM ready handler.

    // Override existing $.event.special.hashchange methods (allowing this plugin
    // to be defined after jQuery BBQ in BBQ's source code).
    special[str_hashchange] = $.extend(special[str_hashchange], {

        // Called only when the first 'hashchange' event is bound to window.
        setup: function () {
            // If window.onhashchange is supported natively, there's nothing to do..
            if (supports_onhashchange) { return false; }

            // Otherwise, we need to create our own. And we don't want to call this
            // until the user binds to the event, just in case they never do, since it
            // will create a polling loop and possibly even a hidden Iframe.
            $(fake_onhashchange.start);
        },

        // Called only when the last 'hashchange' event is unbound from window.
        teardown: function () {
            // If window.onhashchange is supported natively, there's nothing to do..
            if (supports_onhashchange) { return false; }

            // Otherwise, we need to stop ours (if possible).
            $(fake_onhashchange.stop);
        }

    });

    // fake_onhashchange does all the work of triggering the window.onhashchange
    // event for browsers that don't natively support it, including creating a
    // polling loop to watch for hash changes and in IE 6/7 creating a hidden
    // Iframe to enable back and forward.
    fake_onhashchange = (function () {
        var self = {},
          timeout_id,

          // Remember the initial hash so it doesn't get triggered immediately.
          last_hash = get_fragment(),

          fn_retval = function (val) { return val; },
          history_set = fn_retval,
          history_get = fn_retval;

        // Start the polling loop.
        self.start = function () {
            timeout_id || poll();
        };

        // Stop the polling loop.
        self.stop = function () {
            timeout_id && clearTimeout(timeout_id);
            timeout_id = undefined;
        };

        // This polling loop checks every $.fn.hashchange.delay milliseconds to see
        // if location.hash has changed, and triggers the 'hashchange' event on
        // window when necessary.
        function poll() {
            var hash = get_fragment(),
              history_hash = history_get(last_hash);

            if (hash !== last_hash) {
                history_set(last_hash = hash, history_hash);

                $(window).trigger(str_hashchange);

            } else if (history_hash !== last_hash) {
                location.href = location.href.replace(/#.*/, '') + history_hash;
            }

            timeout_id = setTimeout(poll, $.fn[str_hashchange].delay);
        };

        // vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
        // vvvvvvvvvvvvvvvvvvv REMOVE IF NOT SUPPORTING IE6/7/8 vvvvvvvvvvvvvvvvvvv
        // vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
        $.browser.msie && !supports_onhashchange && (function () {
            // Not only do IE6/7 need the "magical" Iframe treatment, but so does IE8
            // when running in "IE7 compatibility" mode.

            var iframe,
              iframe_src;

            // When the event is bound and polling starts in IE 6/7, create a hidden
            // Iframe for history handling.
            self.start = function () {
                if (!iframe) {
                    iframe_src = $.fn[str_hashchange].src;
                    iframe_src = iframe_src && iframe_src + get_fragment();

                    // Create hidden Iframe. Attempt to make Iframe as hidden as possible
                    // by using techniques from http://www.paciellogroup.com/blog/?p=604.
                    iframe = $('<iframe tabindex="-1" title="empty"/>').hide()

                      // When Iframe has completely loaded, initialize the history and
                      // start polling.
                      .one('load', function () {
                          iframe_src || history_set(get_fragment());
                          poll();
                      })

                      // Load Iframe src if specified, otherwise nothing.
                      .attr('src', iframe_src || 'javascript:0')

                      // Append Iframe after the end of the body to prevent unnecessary
                      // initial page scrolling (yes, this works).
                      .insertAfter('body')[0].contentWindow;

                    // Whenever `document.title` changes, update the Iframe's title to
                    // prettify the back/next history menu entries. Since IE sometimes
                    // errors with "Unspecified error" the very first time this is set
                    // (yes, very useful) wrap this with a try/catch block.
                    doc.onpropertychange = function () {
                        try {
                            if (event.propertyName === 'title') {
                                iframe.document.title = doc.title;
                            }
                        } catch (e) { }
                    };

                }
            };

            // Override the "stop" method since an IE6/7 Iframe was created. Even
            // if there are no longer any bound event handlers, the polling loop
            // is still necessary for back/next to work at all!
            self.stop = fn_retval;

            // Get history by looking at the hidden Iframe's location.hash.
            history_get = function () {
                return get_fragment(iframe.location.href);
            };

            // Set a new history item by opening and then closing the Iframe
            // document, *then* setting its location.hash. If document.domain has
            // been set, update that as well.
            history_set = function (hash, history_hash) {
                var iframe_doc = iframe.document,
                  domain = $.fn[str_hashchange].domain;

                if (hash !== history_hash) {
                    // Update Iframe with any initial `document.title` that might be set.
                    iframe_doc.title = doc.title;

                    // Opening the Iframe's document after it has been closed is what
                    // actually adds a history entry.
                    iframe_doc.open();

                    // Set document.domain for the Iframe document as well, if necessary.
                    domain && iframe_doc.write('<script>document.domain="' + domain + '"</script>');

                    iframe_doc.close();

                    // Update the Iframe's hash, for great justice.
                    iframe.location.hash = hash;
                }
            };

        })();
        // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        // ^^^^^^^^^^^^^^^^^^^ REMOVE IF NOT SUPPORTING IE6/7/8 ^^^^^^^^^^^^^^^^^^^
        // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

        return self;
    })();

})(jQuery, this);